Field of the Invention
The present invention relates to a marking device in a tire testing machine for testing tires.
Description of the Related Art
When tires mounted on a vehicle or the like are nonuniform in elasticity, size, or shape in its circumferential direction, the above nonuniform part might cause vibration in rotation at high speed, thus decreasing traveling performance. For this reason, tires undergo performance tests by being examined for circumferential uniformity by means of a tire testing machine after vulcanizing and molding step.
The tires obtained after the performance tests by the tire testing machine are subjected to marking by a marking device. The marking device performs marking by pushing a heated marking pin against a thermal transfer tape, and pressing the tape against the tire to print a desired mark on the tire by the thermal transfer.
For example, JP 2000-329658 A discloses a marking device which is designed to print two markings on a tire. The marking involves arranging two tapes adjacent to each other in a substantially circumferential direction (tangential direction) of the tire, and assigning different marking pins to the respective two tapes. The above-mentioned marking device can print the marks in different colors by using two different colored tapes. Further, JP 2006-95738 A discloses a marking device including two tapes arranged in parallel in a radial direction of a tire. This marking device can mark the same type of tire on its same position while switching between the tapes for use without adjusting the position of the tire in the circumferential direction.
In printing a mark in a predetermined mark position of the tire (for example, a side surface of the tire), such marking devices print the mark in the mark position of the tire by transferring the tire by a tire conveyance device (for example, a belt conveyer) to a predetermined print position where the marking device can mark the tire, and adjusting relative positions of the tire and the marking device according to the conveyance distance.
The tires after undergoing the tests by the tire testing machine are conveyed to the marking device via a sequence of a plurality of tire conveyance devices. However, a stepped portion and the like existing on a connected part between the tire conveyance devices might cause the tire, for example, to slip during the conveyance process, displacing the position of the tire on the tire conveyance device. Such displacement of the position of the tire on the tire conveyance device makes the conveyance distance of the tire conveyance device unstable, thus destabilizing the accuracy of printing on the mark position of the tire which is repeatedly performed by the marking device. Further, in recent years, the design of tires (in particular, side surface of the tire) has been complicated, which restricts the mark position of the tire that can assure stable printing of a mark. Thus, the marking device is required to have a function of being capable of repeatedly printing a mark in a mark position of interest of the tire with high accuracy.
Accordingly, in order to solve the above problems, the present invention has been made, and it is an object of the present invention to provide a marking device in a tire testing machine for testing a tire that can repeatedly print a mark in a predetermined mark position of the tire with high accuracy. Specifically, the marking is performed by conveying the tire after undergoing the test by the tire testing machine for the tire test, to the marking device by means of a sequence of a plurality of tire conveyance devices, and then by accurately aligning and stopping the tire in a predetermined print position upon marking the tire by the marking device.